The Log Cart is an addon in Spintires
Can be installed on trucks such as the Type D537 Truck
This, or the Cart With Crane, is required to attach the Medium Log Trailer , and this is the only way to attach the Long Log Trailer. You need to attach a trailer, you can not deliver logs with this attachment alone.
A log cart requires a log trailer to take a load of logs. The cart holds one end of the logs and the trailer holds the other end.